EU/3/07/484: Orphan designation for the treatment of Leber's congenital amaurosis

Leber's congenital amaurosis is an inherited disease characterised by progressive loss of sight. Approximately 6% of patients affected by Leber's congenital amaurosis have a defective RPE65 gene, and thus do not produce the RPE65 protein in the cells in the eye. Leber's congenital amaurosis is chronically debilitating due to progressive loss of vision.

At the time of designation, Leber's congenital amaurosis affected less than 1 in 10,000 people in the European Union (EU). This was equivalent to a total of fewer than 50,000 people*, and is below the ceiling for orphan designation, which is 5 people in 10,000. This is based on the information provided by the sponsor and the knowledge of the Committee for Orphan Medicinal Products (COMP).

*Disclaimer: For the purpose of the designation, the number of patients affected by the condition is estimated and assessed on the basis of data from the European Union (EU 27), Norway, Iceland and Liechtenstein. At the time of designation, this represented a population of 500,300,000 (Eurostat 2007).

At the time of submission of the application for orphan designation, no satisfactory method had been authorised in the European Union for treatment of the condition. Patients with Leber's congenital amaurosis usually receive genetic counselling and general support such as information and regular medical follow up.

Adenovirus associated viral vector serotype 4 containing the human RPE65 gene is a medicinal product that uses a virus to carry the gene necessary for the production of the protein RPE65. A virus is a small organism capable of introducing genetic material into cells. The type of virus (adeno-associated virus) used in this medicinal product is modified to avoid causing disease in humans.

The evaluation of the effects of adenovirus associated viral vector serotype 4 containing the human RPE65 gene in experimental models is ongoing.

At the time of submission of the application for orphan designation, no clinical trials in patients with Leber's congenital amaurosis had been initiated.

Adenovirus associated viral vector serotype 4 containing the human RPE65 gene was not authorised anywhere in the world for Leber's congenital amaurosis or designated as orphan medicinal product elsewhere for this condition, at the time of submission.

In accordance with Regulation (EC) No 141/2000 of 16 December 1999, the COMP adopted a positive opinion on 12 September 2007 recommending the granting of this designation.

• the seriousness of the condition;
• the existence of alternative methods of diagnosis, prevention or treatment;
• either the rarity of the condition (affecting not more than 5 in 10,000 people in the EU) or insufficient returns on investment.

Designated orphan medicinal products are products that are still under investigation and are considered for orphan designation on the basis of potential activity. An orphan designation is not a marketing authorisation. As a consequence, demonstration of quality, safety and efficacy is necessary before a product can be granted a marketing authorisation.